Cannabis Yields and Dosage (Part 1-b)

Garden adversity

Pollen, pests and plant problems

Contrary to cannabis’ reputation as a weed, it is not so easy to grow quality medicine. Not all gardens have ideal conditions and few patients are trained botanists. The NIDA field data has a solid scientific basis, but it does not reflect all the realities a patient or caregiver faces in obtaining medical-grade cannabis. It is reliable for a mature female garden grown in optimum conditions, but several key factors must be clarified:

• The NIDA Mississippi garden was grown in ideal conditions with full sunlight and fertile, loose, well-drained soil. Many patient gardens are partially shaded or rely on soils of uncertain pH and quality.

• Trained scientists maintain the NIDA garden. Most patients and caregivers are self-taught from books, may overlook serious problems until too late, and seldom have access to expert advice when needed.

• Only mature female plants were considered in the study. Male plants were removed before NIDA made its calculations. Statistically, half of all cannabis plants grown from seed are males with no medical value.

• Only healthy plants were considered. Plants that were sick or died were excluded from the study, but in a real garden this can be a very serious problem.

• NIDA had no loss to theft, pests or law enforcement.

• Unreliable police estimates were listed in the back.

Some gardens yield less than average. Some patients need to grow or store more than a year supply at a time for security issues or as a hedge against crop failure.When seedless (sinsemilla) cannabis goes to seed, the quality drops and net yield of bud goes down by a third (see chart).

When cannabis goes to seed, the usable bud portion drops by more than a third.
After the stem is removed, only 32% of the remaining weight is bud.

Female plants may suddenly become hermaphrodite and grow male flowers. Deer, rodents and snails snack on young plants and can destroy an entire garden. White fly, spider mites, mealy bugs, thrips, aphids and scores of other insects feed on cannabis. A power failure can wipe out an indoor crop light cycle. Molds, fungus and mildew may attack a crop at any time, but are most common just before harvest and can make an entire crop unusable. Floods, frost and other bad weather can destroy an entire garden.

Table 5 below, using data from the DEA study, shows that even big plants may produce less than an eighth of an ounce per square foot. After you remove seeds, that leaves a tenth of an ounce — 1/5 as much as its projected yield, and requiring 500 square feet to obtain three pounds of bud and 1000 square feet for six pounds.
Despite its variables and shortcomings, the best way to estimate crop yields is still measured by the acre — or, in the case of cannabis bud, by the square foot.

Despite its shortcomings, the best way to estimate crop yields is still measured by the acre — or, in this case, by the square foot.

* The derivation of the 48% bud in sinsemilla and 32% bud in seeded cannabis is explained elsewhere.

Indoor and outdoor gardens

More harvests, but smaller plants: An indoor garden often involves many small plants rather than a few large ones. This dry, mature female plant grown indoors weighed only nine grams including bud, stem, leaf and roots. When manicured and finished, it yielded less than three grams — about 1/10 ounce of usable bud. It would take 80 plants this size to yield eight ounces of finished sinsemilla bud.

Compare this plant to the bushy outdoor plant shown here: with many branches and buds, that produced more than five ounces on a single plant.

Different methods, similar yields

Depending on their interest and abilities, individuals may plant a medicine garden outdoors or inside, under electric lamps. Most patients have difficulty gauging their future yield, so barring clear evidence of sales or diversion, even seemingly large gardens may be honest efforts to comply.

Some harvests are better or worse for each grower. Some growers get better yields than others, but most fall in the middle, so using the average is the most reasonable basis to make projections. Outdoor plants typically yield more bud at one harvest per year. Indoor plants each yield less, but allow multiple harvests. Either way, it takes about 200 square feet of garden canopy to obtain six pounds of bud per year.

Outdoors: With a typical growing season that lasts from March or April into September or October, outdoor plants have a long time to grow and usually much more space to spread out, so they tend to be larger.

Half the plants grown from cannabis seed are males that are worthless for marijuana. That’s why outdoor canopy should not be evaluated until flowering is fully underway, usually in August. After that, males are eliminated, leaving gaps in the canopy and giving a better sense of the useable canopy size. Plant canopy need not be continuous. A backyard garden often has plants of different sizes scattered over a wide area. Measure and calculate each plant’s individual canopy then add the total to find the actual area of a garden; e.g., 11 round plants each having a 42” diameter (9 square feet) totals 99 square feet of canopy cover.

The remaining plants are killed with only one harvest per year. To obtain three pounds of sinsemilla bud from 100 square feet of canopy requires a yield of 0.48 ounces per square feet. While the DEA data show an oven-dried average of 0.38 ounces per square foot, by using better genetics, a good grower often harvest a half-ounce of air-cured bud per square foot outdoors.

Outdoors: All Mature together

Plants grow together throughout the season. When flowering begins, the male plants are destroyed.

Indoors: Two growth cycles

About half of the indoors is for mothers, seedlings, clones and young plants that will be used to refill the flowering area as needed.

100 square feet of mature female canopy from seed or clone is harvested at one time outdoors, with a total yield of ±50 ounces (3.1 pounds) of bud to last the entire year.

The other half area indoors is used for flowering females, harvested three times a year, for a total of 56.25 ounces per year.

Indoors: A personal indoor garden typically fits into one or two average size rooms using electric lamps, fans and basic garden supplies. While an indoor garden is typically harvested three times a year, its annual yield is often about the same as outdoors.

Only part of an indoor garden is used for flowering at any given time. The rest is nursery and vegetative area that does not produce bud. Cannabis is light sensitive, so a barrier must separate vegetative from flowering areas. If half a 100 square foot area is used to obtain flowers three times a year, a total of 150 square feet of bud canopy is harvested. The typical indoor yield range is 0.25 to 0.5 ounces per square foot, averaging 0.38 ounces, so those 150 square feet should yield 56.25 ounces (3.5 pounds), just over one ounce per week.

Once a patient has an adequate supply, they can periodically shut down an indoor flowering area but keep the nursery going for future use. Any supply of cannabis or garden canopy that is larger than the local guidelines or statewide default amounts should be accompanied by a physician’s written authorization whenever possible. This allows for a small buffer against adversity and crop loss and lets law enforcement know that the supply is legitimate for the patient’s current needs.

Warning: Electrical overloads and lamp heat can cause fires. Be sure your wiring is up to code. Most homes cannot support more than 3500 extra watts. Also beware of flooding, mold and odors.

Measuring canopyLarger gardens give bigger yields

Some people can grow bushy plants outdoors, others need to grow small “Sea of Green” gardens with tiny plants indoors. Safe Access Now garden guidelines are easy to use and follow for either circumstance. All you need is a tape measure to calculate the canopy size.

Consider the overall plant and garden configuration, layout and density, then do the math:

3) If a garden is irregular in shape or isolated plants are scattered throughout an open area, measure individual plant canopies or patches of filled-in area that the plants occupy, not the open space between them. Calculate for each plant or patch and repeat; add to find the garden total.

Remember that indoors or out, only the mature flowering area provides usable cannabis bud. After they are ripe, the plants must still be cut, dried, manicured, cured and processed before they are ready to use.

Many small plants or a few big ones?

The following reference chart shows how many rounded plants of similar size can fit within 100 square feet of total garden canopy: Individual plant size

1 plant at 9-11′ diameter each

2 at 7-8′ diameter

3 at 6′ diameter

5 at 5′ diameter

7 at 4′ diameter

14 at 3′ diameter (typical outdoor girth)

33 plants at 2′ diameter

99 plants at 1 foot diameter.

Most gardens naturally produce an assortment of plants of different sizes. A typical mature outdoor garden might hold two plants at 4’ diameter, six at 3’, four at 2’ and 12 at 1’ diameter for a total of 24 plants in 92 square feet. A typical indoor garden might include 12 flowering plants in 32 sq’ area, 24 vegetative in 32 sq’, 4 mothers in 24 sq’, and 48 starters in 8 sq’, for a garden total of 88 plants in 96 square feet.

How many are too many? It depends. Since a few large cannabis plants can out-produce hundreds of small ones, the number of plants in a garden cannot accurately predict yield. Canopy indicates a garden’s likely yield without counting plants, knowing if they are seedlings or clones, etc. A 99-plant cap fits below the federal five year mandatory sentence and ensures that state jurisdiction applies. The California default guidelines in SB 420 protect from arrest only eight ounces of bud and six mature or 12 immature cannabis plants per patient.